The agency released a statement Monday titled "A Knockout for Taxpayers."

It said it is investigating people who claimed to have small incomes while paying up to $7,500 each to travel to Nevada to watch Saturday's fight between world welterweight champion Floyd Mayweather Jr. and Argentine boxer Marcos Maidana.

The agency says those 17 people have since been removed from a list of low-income Argentines and must now pay taxes consistent with their large expenses. It says one also has a $150,000 Porsche.

The agency says it will now enforce stricter controls on Argentines attending sporting events abroad, including the soccer World Cup in Brazil that kicks off on June 12.